I would like to coat fluorescent PLA in clear, transparent varnish, and I am looking for a product that does not block UV rays. Is there anything like that?

1 Answer 1


It looks like both acrylic and polyurethane should transmit near UV - the sort of UV you need. Getting actual transmission spectra of specific varnish products isn't likely to happen, but I've skimmed a few papers.

Acrylic varnish is commonly used on PLA.

You need to be careful though not to get a UV-curing product (you're unlikely to do this by accident), but also not to get one designed to slow the effects of UV of the item, as some wood varnishes are supposed to do.this is a selling point, so you'll need to look for varnishes that say nothing about UV - and probably run a test to be certain.

  • Yes, exactly, the problem is as soon as I put anything like "UV" in the query, I will find exactly those products, UV-curing and UV-blocking... Oct 17, 2023 at 18:37
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    @ThomasHirsch UV-blocking is typically a selling point for varnishes that have that property, while the reverse (UV-permeable) is not; search without that term and check the product descriptions to have better luck
    – Allison C
    Oct 17, 2023 at 18:53
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    Well said @AllisonC. I think I need to edit that in.
    – Chris H
    Oct 17, 2023 at 19:05

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